This invention relates to the protection of plants from diseases caused by airborne carriers, e.g. spores, bacteria, etc. by application of a W/O emulsion of a block-like paraffin film having substantially the same number of carbon atoms as is naturally present on the surface of the plant.
The naturally occurring paraffin layer of most plants is inadequate to prevent transpiration and attack by micro-organisms, spores and the like.
It is generally known to apply paraffin films to plants for the purpose of preventing transpiration and attack by microorganisms.
These films were not entirely satisfactory due to the fact that the paraffin employed was phytotoxic or incompatible with that naturally present on the plant surface. Moreover, these paraffins were applied to the plant surface as an emulsion and the emulsifier employed often caused the resulting paraffin film to be incompatible with the natural paraffin film on the plant surface.
A significant advance in this area was disclosed in applicant's Japanese Pat. No. 46-4964 which utilized an emulsion of a paraffin having the same number of carbon atoms as that naturally present on the plant and employed fatty acid emulsifiers.
However, because of the manner in which the emulsion in Japanese Pat. No. 46-4964 was prepared, the colloidal particles in the emulsion were as large as 5 to 10 microns.
In this regard, the emulsion of the Japanese patent is prepared by a batch process which involves heating paraffin and fatty acid soap emulsifier to about 90.degree. to 100.degree. C. under stirring to form a solution. When the hot emulsion is permitted to cool, i.e. in a cooling bath, the colloidal particles of paraffin tend to crystallize on the walls of the container but remain in solution in the internal portion of the container. As the batch is stirred, the crystallized paraffin tends to the entire batch is cooled to about 40.degree. C., the particles of paraffin are crystallized and stabilized at a particle size of above 5 microns, i.e. up to 10 microns.
An emulsion containing such large particles is not economical because it will not retain its efficacy when diluted with water, e.g. to a 200x dilution.